|High School|Join Year|From|Left|league left to|
|---|---|---|---|---|
|Ainsworth|1954||1961|Big Nine Conference|
|Atherton|1960||1976|Mid-Eastern Eight Conference|
|Beecher|1950||1960|Big Nine Conference|
|Bendle|1950||1975|Mid-Eastern Eight Conference|
|Bentley|1960||1978|Genesee Eight|
|Brandon|1977||1978|Five County 5 League|
|Clio|1950||1960|Big Nine Conference|
|Davison|1950||1960|Big Nine Conference|
|Durand|1964||1978|Flint Metro League|
|Fenton|1940||1968|Flint Metro League|
|Flushing|1950||1960|Big Nine Conference|
|Grand Blanc|1950||1960|Big Nine Conference|
|Hartland|1976||1978|Five County 5|
|Kearsley|1950||1960|Big Nine Conference|
|Lake Fenton|1976||1978|Genesee Eight|
|LakeVille|1956 2nd: 1964||1962 2nd: 1976|Independent 2nd: Flint Metro League|
|Linden|1974||1978|Genesee Eight|
|Mt. Morris|1950||1960|Big Nine Conference|
|Swartz Creek|1960|County C League|1968|Flint Metro League|

Question: how many schools left the genesee county b league before ainsworth?
Answer: 7